1. Field
This disclosure relates generally to semiconductors, and more specifically, to the testing and sale of semiconductors.
2. Related Art
As integrated circuits evolve and incorporate significantly more amounts of circuitry, the ability to reliably manufacture large percentages of fully functional integrated circuit products on a single semiconductor wafer has become very difficult. The yield of good die that exists on a wafer therefore is often lower for a complex integrated circuit and a low yield results in a significant amount of lost revenue for a manufacturer.
To improve yield results, others have incorporated redundant circuitry onto an integrated circuit. The redundant circuitry is selectively used after an integrated circuit is tested to replace identified defective circuitry. However, as large amounts of circuitry have been incorporated into an integrated circuit the amount of redundancy required to insure that failing circuitry can be replaced is often cost and size prohibitive. As a result the yields of complex integrated circuits are often much lower than desired.
As integrated circuits advance in function and complexity, multiple data processors have been incorporated onto a single integrated circuit. When such integrated circuits are tested, each of the data processors within the integrated circuit is typically serially tested in an assigned order. Disadvantages with known testing methodologies include the increased time to test complex integrated circuits and the high cost associated with the electronic testers which determine the functionality of the integrated circuit. Test equipment to perform diagnostic testing for complex integrated circuits typically costs in excess of one million U.S. dollars and thus represents a significant investment for an integrated circuit manufacturer. To reduce test time, others have tested multiple processors in parallel. In such test methodologies, a comparison between the outputs of the multiple processors is made to indicate whether all of the processors are providing the same result or a different result. When a different result is indicated a failure of the circuitry is noted by the test equipment.